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You said in the off cycle right? Probably your float is closed because there is not any high press. gas going under the float. This holds a level in the condenser and if you have chilled water flowing it transfers the "cold" to the refrigerant in the condenser.

sorry only the cond was sweating about half way up. it was sweating bad enough that we needed to mop up the floor beneath it several times. it was just overhauled 2 seasons ago and we have never seen this before. CHW pump was on with a 45 loop CW pump was off with 70 water

That is your problem, the refrigerant is at 45 degrees or whatever your chiller loop is at. This is normal if you run water through it. If it bothers you insulate the botom of the condenser or cool your machine room.

Maybe you never saw the sweating in the past because when you looked at the chiller after shutdown, enough time had passed that the refrigerant in the condenser had all migrated to the cold evaporator, and the now empty condenser had warmed to room temperature. If you have multiple chillers, and are pumping chill water through an idle chiller, you are wasting energy. And at times, may be running an additional chiller when it is not really needed.

Spinning wheel is correct but insulating the barrel is not the answer. The correct course of action is to install an automatic isolation valve (assuming there is none) on the CHWS line of each cooler. This will stop the chilled water from flowing through the lag chiller preventing the condensation from forming. It will also increase the overall efficiency of the plant by preventing the short circuiting of CHWR into the CHWS through the lag chiller.

If the machine does have an automatic CHW valve, then check it and find out why it isn't closing when the chillers off.

Curious what the condenser refrigerant temp is when this is happening. Also you said it sweats when off for the weekend..does this mean its still sweating after a couple of days being idle? XL's are prone to "sticky" floats but typically shows up when she's running..fluctuating motor current etc..refrigerant MUST be transferring from cond for this to happen.